There is no "40 man" salary that I know of, except they start getting yearly raises.
You could theoretically wait until pre-season to demote and ensure no demotion hit.
He will get paid 343K or whatever the next 10% raise is for the player in question, however the following season he will revert back to AAA salary. NOT AAA minimum, but FAR LESS than 300K+. While they do get raises every season, it is only a few grand per season.
Here's an example
Sticky Clyburn.
After placing him on the 40 he went up from 55K to 57K, but not until the following season. I called him up to the BL the next season and didn't demote until the following pre-season for exactly the same reason as above. He made 343K that season, then reverted back to AAA money @ 62K the next. He has increased from there as follows: 65K, 68K, 71K, 74K, 77K, 80K, 84K.
10/2/2013 2:47 AM (edited)